Cryptography is a well-known technique for providing secure communication between two or more parties. Authenticated Key Agreement is a cryptographic protocol where two or more participants, authenticate each other and agree on a key for future communication. These protocols could be symmetric key or asymmetric public key protocols. Recall that symmetric key protocols require an out-of-band security mechanism to bootstrap a secret key, while public key protocols require certificates and large scale public key infrastructure (PKI). Clearly, public key methods are a bit more flexible, however, the requirement of certificates and a large scale public key infrastructure has proved to be challenging.
Recently, Identity Based Encryption (IBE) protocols have been proposed as a viable alternative to public key methods by simplifying the PKI requirements and replacing them with a simple Key Generation Function (KGF) to generate private keys. However, one significant limitation of existing IBE methods is that the KGF can end up being a de-facto key escrow server with undesirable consequences. That is, since the KGF in the existing IBE protocol generates each private key used in the protocol, KGF can therefore decrypt all exchanges. This is an undesirable consequence since if KGF was compromised by an intruder, then exchanges between the two parties operating under the protocol would be compromised as well.
Thus, a need exists for an improved identity based authenticated key agreement protocol.